There are products in the market place today that enable a single display device to be used for the viewing of 3D stereoscopic images. These employ a variety of techniques. One technique uses shuttered glasses and involves displaying alternate images for the left and right eyes where the images for the left eye are viewed only with the left eye and the images for the right eye are viewed only with the right eye. The shuttered glasses are synchronized with the display device and block the view of the left eye when the right image is displayed and vice-versa. The images seen are such that the brain joins these images together into a single virtual image that appears to be 3 dimensional. Such a system is described in U.S. Pat. No. 4,562,463, to Lipton.
Another technique involves painting two interleaved polarized images, on a specialized screen, simultaneously, one polarized vertically to be viewed by the left eye and one polarized horizontally to be viewed by the right eye. These images are then viewed through polarized glasses which contain a vertically striated filter for the left eye and a horizontally striated filter for the right eye. As a result each eye sees a different image and once again the images are such that the brain joins these images together into a single virtual image that appears to be 3 dimensional.
Other well known techniques used for displaying 3 dimensional images include the use of colored filters, mirror displays etc. However, such techniques are only used for creating the appearance of a 3 dimensional image based on two, slightly offset, views of the same image.
U.S. Pat. No. 5,497,270, to Rud, shows an apparatus and method for increasing resolution and expanding the displayed field of view for 2 dimensional images. This uses a complex system of lenses, partially reflective mirrors and polarizing cells that are used to alternately display the collimated left and right fields of view of an image to the viewer. This solution is applied to wide angle virtual reality systems such as head up displays and enable the user to see a wider, more detailed image than is otherwise possible.
However, none of these solutions provides a simple and adjustable means for creating a 2 dimensional virtual image that can be viewed on a display device with a viewable width that is narrower than the image seen. Simplicity is important to make the solution more widely available. Adjustability is necessary because individuals have different capabilities for viewing 2 dimensional virtual images and so the image must be displayed in a manner sympathetic to the capabilities of the viewer.